hello all, just wondering would anyone out there have some troubleshooting tips!

O.k when i initially start my car in the mornings it sounds like the car is spitting an farting every now and again until the car has warmed up (drive it for five or ten minutes) then the car idles fine. i reciently changed the oil and plugs as i thought this might have an input into it however i was wrong.

next on the list is to maybe replace the O2 sensors?????

Any help??